Does it happen when you start Thunderbird soon after you open your session or when something else happens in the background?

I use Thunderbird Portable, so it's the same edition I use on two different computers. I had noticed a problem happening about 50 % of the time on one computer and never on the other one. In my case, I got what seemed the complete page, but menus were not active and nothing happended. I had to force-quit Thunderbird and restart it and then everything was fine.

It turned out that I was usually starting Thunderbird right after I opened my computer session. In the background, I also have a Google Drive sync on that computer. The sync is a bit disk intensive, so the mechanical disk was a bit delayed. I concluded that it sounds like Thunderbird allows, say, 30 seconds to fully open; if it doesn't, then it freezes. Now I make sure to open Thunderbird by itself, then only start other applications when Thunderbird is fully open. No issues since then.

So as a solution, I would suggest that you make sure you start Thunderbird when no other major activity occurs at the same time. For example, don't start Thunderbird, Word, Photoshop and Firefox at the same time...